1. Field of The Invention
This invention relates to athletic socks, particularly socks worn in relatively stiff boots, where foot comfort may be a problem. Socks of the present invention are especially designed for use by persons engaged in winter sports, e.g. ice skating, skiing, mountain climbing, outdoor camping and snowboarding, where boots are worn.
2. Prior Developments
Persons engaged in winter sports often wear relatively stiff boots, as protection against snow or the weather elements entering into the footwear to thereby make the feet feel unconfortable. However, the stiffness of many boots is itself a source of foot discomfort. The problem is more difficult since the boot has to feel comfortable, while at the same time keeping the feet warm. One solution is to wear multiple pairs of socks, so as to increase the cushioning action and the thermal insulative action.
Boots used in snowboarding have metal eye loops and laces that can be a source of foot discomfort. The binding system requires the wearer to buckle the binding down tight into the foot, which in turn presses the eye loops of the boot into the top (instep) of the foot, causing some foot discomfort. Boots used in other sports, such as ice skating, skiing and hiking, have similar problems. The problem of keeping the feet comfortable and warm in sub-freezing temperatures, is affected partly by the fact that sweat or moisture generated by the athletic activity (e.g. ice skating) tends to work through the sock so as to form a thermal bridge between the boot and the person's foot. Heat travels from the foot through the relatively conductive moist sock material to the relatively cold boot, thereby rapidly cooling the foot to an undesirably cold and uncomfortable condition.
In an effort to avoid such undesired heat loss there have been developed socks formed of imperforate neoprene. The neoprene, in sheet form, acts as a thermal barrier to slow down, or completely stop, the escape of heat from the person's foot to the boot. An imperforate neoprene sock fully encircling the person's foot is however not fully satisfactory, since it may prevent the foot from perspiring or breathing in normal fashion. The complete thermal barrier provided by an imperforate neoprene sock traps sweat between the persons's skin and the neoprene surface, such that a resistance to further sweating is established. The foot senses the resistive condition and stops sweating, thereby eventually causing the skin surface to cool down to an undesired extent.
Various porus, moisture-abosorbent socks have been developed as an alternative to the imperforate neoprene sock. U.S. Pat. Nos. 3,341,096 and 4,898,007 and 5,095,548 are representative patents showing socks knitted out of various hydrophilic and hydrophobic yarns in different combinational arrangements, so as to control the escape of moisture from the person's foot.
A hydrophilic yarn, such as cotton, is moisture-absorbing and moisture conducting, so as to act like a wick for transporting moisture from a relatively wet area of the sock to a relatively dry area. A hydrophobic yarn has relatively slight affinity for water, such that the moisture tends to collect on the yarn surface, where it can be removed by evaporation or collect as free condensate, depending on its temperature.
The above-mentioned patents show sock constructions, wherein some areas of the sock are formed primarily of hydrophilic yarns, and other areas of the sock are formed primarily of hydrophobic yarns, whereby moisture generated by the person's foot is transported to specific areas of the sock for evaporative removal. Heat is retained in the in the moist sock material so as to keep the person's foot relatively warm and comfortable. Water has a relatively high specific heat, so that a relatively thin film of water on the sock is able to hold relatively large quantities of heat.
The porosity of the knitted socks described in the above-noted patents, may be a problem in that the moistened yarns and yarn surfaces may form unobstructed thermal paths between the person's foot and the boot interior surface, such that the socks will not serve their intended when worn for prolonged periods of time in sub-freezing conditions.
U.S. Pat. No. 4,373,361 to I. Thornelburg, shows a knitted ski sock formed of hydrophilic and hydrophobic yarns for heat management purposes. Additonally the yarn layers are increased or thickened in selected areas of the sock so as to form a cushion between the boot and the person's skin. The cushion acts as a spacer, thereby making the sock more comfortable on the person's foot.